This invention relates generally to display signs and is particularly directed to a flat, multiple panel, alphanumeric character display having an illuminated, or high contrast, background.
Signs for displaying information in the form of alphanumeric characters or other form of symbology are well known and take on a variety of forms. Perhaps the most common form of this type of display involves the use of individual, replaceable panels each containing an individual symbol or alphanumeric character. The panels are typically mounted in the forward, open portion of a box-like frame and are held in position by means of generally horizontally oriented tracks attached to the front portion of the sign frame. The characters, or letters, are arranged in horizontal rows for presenting the message which the sign is intended to convey. The lettered panels are arranged in accordance with the desired message and may be easily removed from or relocated on the sign.
Signs of this type frequently make use of reverse-type letters wherein the letter, or symbol, is presented as a clear, or transparent, portion of the individual panel surrounded by an opaque panel portion for defining the letter. For increased visibility and definition, a background which is in high contrast with the opaque portion of the panels is provided aft of the panel array. In addition, frequently a source of illumination is provided aft of the background panel for nighttime viewing. For optimum clarity and resolution, the high contrast background should be visible only through the transparent portions of the lettered panels which define the individual symbols, or alphanumeric characters. Therefore, the forward surface of the sign should be free of "light leaks".
The prior art discloses various attempts to eliminate, or at least minimize, these light leaks, particularly in illuminated signs. U.S. Pat. No. 1,521,177 to Friis et al discloses an electrically illuminated sign including sign character openings which are divided into equal spaces or divisions by means of upright division bars which engage immediately adjacent glass sign character plates and stencil plates in an overlapping manner so as to attempt to reduce light leaks. The fixed inter-panel division bars are mounted as an integral part of the sign frame and will thus not accommodate panels of various widths. U.S. Pat. Nos. 2,632,270 to Moss and 3,742,633 to Palm disclose arrangements in which the opaque lateral edges of each letter panel are adapted to overlap and engage the facing lateral edge of an immediately adjacent letter panel so as to substantially reduce light leaks between letter panels. This approach requires the lateral edges of each panel to be formed into a complementary, interconnecting shape, such as by routing, and is therefore expensive and time-consuming. U.S. Pat. No. 1,638,679 to Buchanan discloses a circular sign arrangement including a plurality of individual stenciled letters or numbers each of which includes an extended portion located on a lateral edge of the stencil and adapted to fit under an adjacent stencil when assembled in a circular or linear array on the sign. In addition, metal clips may be positioned between adjacent stencil letters in an attempt to eliminate light leaks therebetween. This approach is limited in application to panels comprised of a malleable material such as metal and would be difficult and expensive to implement with some of the more common lettering materials in use today such as the harder plastics. U.S. Pat. No. 2,928,198 to Madanick illustrates yet another approach to a multi-letter illuminated sign.
The present invention is intended to overcome the aforementioned limitations of the prior art by providing an inexpensive, easily assembled, planar sign arrangement in which light leaks between adjacent letter panels are eliminated. The individual letter panels and inter-letter partitions affixed thereto are easily fabricated and assembled with the resulting combination easily installed in a conventional display sign.